.woocommerce-product-gallery .video-thumbnail {
    position: relative;
    background: #000;
    border: 2px solid #fff;
    border-radius: 4px;
    overflow: hidden;
}

.woocommerce-product-gallery .video-thumbnail::before {
    content: '';
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    width: 0;
    height: 0;
    border-style: solid;
    border-width: 15px 0 15px 25px;
    border-color: transparent transparent transparent #fff;
    z-index: 1;
}

.woocommerce-product-gallery .video-thumbnail::after {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0.5);
}